An image projection system which connects images projected by two or more image projection devices on one screen to one another to generate a single image, and displays the single image needs to move the positions of the projected images and to deform the projected images so that the projected images can be smoothly connected to one another at their connection points. Generally, this movement processing and deformation processing are called a geometric correction.
Because it is necessary to grasp the positions on the screen of the images projected by the two or more image projection devices, and overlapping of the two or more projected images, etc. in order to carry out this geometric correction, an image capturing device for capturing the images projected by the two or more image projection devices is disposed.
On the other hand, there is provided a prior art image geometric correction device which needs to capture, as a single image, two or more images projected onto a whole screen without distortion in order to capture the two or more projected images in a state in which they actually overlap one another to determine overlapping of the two or more projected images, and in order to calculate the amount of image geometric correction correctly.
For this purpose, it is necessary to place an image capturing device at a position which it can capture the whole screen with one time capturing so that it is just opposite to the screen (for example, refer to patent reference 1).    [Patent reference 1] JP, 2000-350230, A
A problem with the prior art image projection system constructed as mentioned above is that it is necessary to strictly place an image capturing device at a predetermined position in order to capture, as a single image, images projected onto a whole screen in a state in which all image projection devices project the images on the screen.
The present invention is made in order to solve the above-mentioned problem, and it is therefore an object of the present invention to provide an image projection system and an image geometric correction device which can divide an image which consists of projected images on a whole screen into two or more images and capture them, and which can make a geometric correction to the projected images without strictly placing image capturing devices at predetermined positions.